The present invention relates to a probing method and a probing device suitable for use to test semiconductor devices such as IC chips formed on a silicon wafer.
In the manufacturing process of semiconductor devices, after a wafer process has been completed and further IC chips have been completely formed in a silicon wafer, electrical measurements (termed probe test) are effected to examine the presence or absence of shorts or disconnections in formed electrode patterns and the input and output characteristics of the completed IC chips. That is, the acceptance or rejection of the IC chips is discriminated with respect to quality under the condition of the semiconductor wafer (referred to as wafer, hereinafter). After that, the wafer is divided into a plurality of IC chips. Further, the accepted IC chips are packaged, and further subjected to a handler test as to other items to finally determine the acceptance or rejection of the IC chip products.
In the probing device as described above, a wiring substrate (termed probe card) provided with a plurality of needles is used. This probe card has an insulating substrate, on one surface of which a group of contacts is arranged. Further, a plurality of needles (probes) made of tungsten, for instance, are provided on the insulating substrate. One end of each needle is connected to one of the contacts and the other end of each needle extends obliquely from the other surface of the insulating substrate. For an electrical test or inspection, contacts formed in the probe card are electrically connected to electrodes of a test head, and further the needles (probes) are brought into contact with electrode pads formed on the IC chips by moving a wafer mounting base for position matching between the needles and the electrode pads. After that, high frequency test signals equivalent to the operational speed of the IC chips are inputted to the IC chips from the test head through the probe card, and further the test signals outputted from the IC chips are returned to the test head, to electrically test the IC chips on the basis of the signals outputted by the IC chips to be tested.
By the way, recently there exists such a tendency that the semiconductor devices have been microminiaturized and highly integrated more and more, so that the electrode pads of the IC chips are being miniaturized and further the arrangement pitch of the electrode pads is being reduced more and more. At present, the size of the electrode pads is about 70 .mu.m on one side thereof and the tip diameter of the needle is about 30 .mu.m. However, when the electrode pads are further miniaturized and thereby the pitch thereof is further reduced, it is extremely difficult to arrange the needles so as to be brought into contact with the electrode pads.
To overcome the above-mentioned problem, the inventor is now studying the method of forming the probe card as follows: a flexible thin film formed of polyamide resin is used; conductive projections (referred to as bumps) formed of gold 18 carats fine or copper, for instance, are arranged as contacts or needles on one surface of the this flexible film; and a wiring multilayer, connected to the bumps, respectively is formed inside the flexible thin film.
In the probe card formed as described above, it is possible to form microminiaturized bumps on the insulating substrate according to a predetermined arrangement pattern in accordance with the printing technique.
On the other hand, in the case of the burn-in test for previously detecting defective IC chips under severer conditions than usual, the IC chips are so far tested after having been packaged. Recently, however, it has been studied to conduct the burn-in test of the IC chips under the conditions of the wafer. In this case, a temperature adjuster is incorporated in the wafer mounting base, and the wafer is tested under the condition that the test temperature is adjusted within such a wide range as between -40.degree. and +150.degree. C., for instance.
In the case of the above-mentioned probe card, however, since there exists a big difference in coefficient of thermal expansion between the flexible thin film resin (e.g., polyamide, 3.1.times.10.sup.-5) and the silicon wafer (2.42 .times.10.sup.-6), in such a sever and wide temperature test from room temperature to 100.degree. C. or higher as described above, the matching positions of the bumps relative to the electrode pads as adjusted at room temperature are easily dislocated markedly within the large temperature range. The change rate of the matching positions between the bumps and the electrode pads increases with increasing area of the wafer, that is, with increasing wafer diameter.
Therefore, even if the bumps are formed on the flexible thin film so as to confront the electrode pads arranged on the wafer at room temperature, since the size of the electrode pads is extremely small and in addition the pitch of the electrode pads is narrow (with the result that the bump size is reduced to that extent), the electrical contact conditions between the bumps and the electrode pads are deteriorated, or the pumps are easily dislocated from the electrode pads at the worst at another higher or lower temperature. In other words, even if the method of forming bumps on the thin film is adopted, there still exists a problem in that it is impossible to perform the test reliably by use of a probing device, due to the recent advance of the device integration rate, microminiaturization, and wafer diameter.